The total repurchase amount authorized by an entity's Board of Directors under a debt repurchase plan.

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Interest rate on the amount to be repaid to the counterparty to the repurchase agreement when the carrying amount (or market value, if higher than the carrying amount) of securities or other assets sold under the repurchase agreement exceeds 10 percent of total assets.

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Face (par) amount of debt instrument at time of issuance.

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Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

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Contractual interest rate for funds borrowed, under the debt agreement.

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The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

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The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

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Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

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The cash outflow for the settlement of long-term borrowing, with the highest claim on the assets of the entity in case of bankruptcy or liquidation, as it matures.

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Including the current and noncurrent portions, aggregate carrying amount of all types of notes payable, as of the balance sheet date, with initial maturities beyond one year or beyond the normal operating cycle, if longer.

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The aggregate amount of the participating mortgage obligation at the end of the accounting period.

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The carrying amount, as of the date of the latest financial statement presented, of loans receivable which are owned but transferred to serve as collateral for the payment of repurchase obligations, and for which the transferee is not permitted to sell or re-pledge them to an unrelated party.

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The cash inflow from a contractual arrangement with the lender, including letter of credit, standby letter of credit and revolving credit arrangements, under which borrowings can be made up to a specific amount at any point in time with maturities due beyond one year or the operating cycle, if longer.

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The cash outflow for the settlement of obligation drawn from a contractual arrangement with the lender, including letter of credit, standby letter of credit and revolving credit arrangements, under which borrowings can be made up to a specific amount at any point in time with maturities due beyond one year or the operating cycle, if longer.

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Amount of cash and cash equivalents restricted as to withdrawal or usage. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset.

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Notes Payable - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Notes Payable - Narrative (Details) - USD ($) $ in Millions	Mar. 31, 2020	Jun. 30, 2020	May 01, 2020	Feb. 01, 2020	Oct. 01, 2019	Sep. 30, 2019
Debt Instrument [Line Items]
Notes payable		$ 4,297.3				$ 3,399.4
Outstanding letters of credit		159.4
Restricted Cash and Cash Equivalents		19.2				19.7
Home Building [Member]
Debt Instrument [Line Items]
Unamortized Debt Issuance Expense		11.7				5.4
Notes payable		2,490.3				2,047.6
Authorized repurchase of debt securities		500.0
Restricted Cash and Cash Equivalents		$ 9.0				8.0
Home Building [Member] \| SeniorNoteFortyTwo [Member]
Debt Instrument [Line Items]
Stated interest rate					2.50%
Debt Instrument, Face Amount					$ 500.0
Debt Instrument, Interest Rate, Effective Percentage					2.70%
Home Building [Member] \| 4.0% senior notes due 2020 [Member]
Debt Instrument [Line Items]
Stated interest rate		4.00%
Maturities of Senior Debt	$ 500.0
Home Building [Member] \| SeniorNoteFortyFour
Debt Instrument [Line Items]
Stated interest rate			2.60%
Debt Instrument, Face Amount			$ 500.0
Debt Instrument, Interest Rate, Effective Percentage			2.80%
Financial Services [Member]
Debt Instrument [Line Items]
Notes payable		$ 1,172.9				888.9
Borrowing capacity on revolving credit facility		1,350.0
Maximum borrowing capacity on revolving credit facility		1,575.0
Restricted Cash and Cash Equivalents		10.0				11.6
Mortgage loans held for sale pledged under repurchase agreement		1,390.0
Mortgage loans held for sale pledged under repurchase agreement, collateral value		$ 1,360.0
Interest rate on mortgage repurchase facility		2.40%
Forestar Group [Member]
Debt Instrument [Line Items]
Unamortized Debt Issuance Expense		$ 9.4				6.2
Notes payable		640.6				460.5
Borrowing capacity on revolving credit facility		380.0
Letter of Credit, Maximum Borrowing Capacity (in dollars)		100.0
Maximum borrowing capacity on revolving credit facility		$ 570.0
Letters of credit, sublimit borrowing capacity, as a percentage		50.00%
Outstanding letters of credit		$ 31.6
Line of Credit Facility, Remaining Borrowing Capacity		348.4
Restricted Cash and Cash Equivalents		$ 0.0				0.0
Forestar Group [Member] \| 3.75% convertible senior notes due 2020 [Member]
Debt Instrument [Line Items]
Stated interest rate		3.75%
Maturities of Senior Debt	$ 118.9
Forestar Group [Member] \| Senior Note Member Forty One [Member]
Debt Instrument [Line Items]
Stated interest rate		8.00%
Debt Instrument, Face Amount		$ 350.0
Forestar Group [Member] \| Senior Note Member Forty Three
Debt Instrument [Line Items]
Stated interest rate				5.00%
Debt Instrument, Face Amount				$ 300.0
Debt Instrument, Interest Rate, Effective Percentage				5.20%
Forestar Group [Member]
Debt Instrument [Line Items]
Notes payable		640.6				462.9
Borrowings outstanding on revolving credit facility		0.0				0.0
Forestar Group [Member] \| 3.75% convertible senior notes due 2020 [Member]
Debt Instrument [Line Items]
Notes payable		$ 0.0				119.1
Stated interest rate		3.75%
Forestar Group [Member] \| Senior Note Member Forty One [Member]
Debt Instrument [Line Items]
Notes payable		$ 344.8				343.8
Stated interest rate		8.00%
Forestar Group [Member] \| Senior Note Member Forty Three
Debt Instrument [Line Items]
Notes payable		$ 295.8				0.0
Stated interest rate		5.00%
Home Building Consolidated
Debt Instrument [Line Items]
Repayments of Long-term Lines of Credit		$ 1,060.0
Notes payable		2,483.8				2,047.6
Borrowing capacity on revolving credit facility		1,590.0
Maximum borrowing capacity on revolving credit facility		$ 2,500.0
Letters of credit, sublimit borrowing capacity, as a percentage		100.00%
Proceeds from revolving credit facility		$ 1,060.0
Borrowings outstanding on revolving credit facility		0.0				0.0
Outstanding letters of credit		127.8
Line of Credit Facility, Remaining Borrowing Capacity		1,460.0
Home Building Consolidated \| Short-term Debt [Member]
Debt Instrument [Line Items]
Borrowing capacity on revolving credit facility		375.0
Maximum borrowing capacity on revolving credit facility		550.0
Proceeds from revolving credit facility		0.0
Home Building Consolidated \| 5.75% senior notes due 2023 [Member]
Debt Instrument [Line Items]
Notes payable		$ 398.6				398.4
Stated interest rate		5.75%
Home Building Consolidated \| SeniorNoteFortyTwo [Member]
Debt Instrument [Line Items]
Notes payable		$ 496.2				0.0
Stated interest rate		2.50%
Home Building Consolidated \| 4.0% senior notes due 2020 [Member]
Debt Instrument [Line Items]
Notes payable		$ 0.0				499.6
Stated interest rate		4.00%
Home Building Consolidated \| SeniorNoteFortyFour
Debt Instrument [Line Items]
Notes payable		$ 494.8				0.0
Stated interest rate		2.60%
Maximum [Member] \| Financial Services [Member]
Debt Instrument [Line Items]
Borrowing capacity on revolving credit facility		$ 1,800.0
Segment Reconciling Items [Member]
Debt Instrument [Line Items]
Notes payable		0.0				2.4
Restricted Cash and Cash Equivalents		$ 0.0				$ 0.0